Question 1

Which of the following statements best describes the law of conservation of mass?

Accepted Answer

In a chemical reaction, matter is neither created nor destroyed; the total mass remains constant.

Question 2

A sample of ammonia (NH$$_3) $$contains 10.0 g of hydrogen. Given the nitrogen-to-hydrogen mass ratio in ammonia is 4.7:1, how many grams of nitrogen are present?

Accepted Answer

$$47 g$$

Question 3

Which of the following is an example of a physical change?

Accepted Answer

Water boiling to form steam

Question 4

Which statement best distinguishes the law of definite proportions from the law of multiple proportions?

Accepted Answer

The law of definite proportions applies to two or more samples of the same compound, while the law of multiple proportions applies to two different compounds containing the same two elements.

Question 5

Which subatomic particle was discovered by J.J. Thomson using the cathode ray tube experiment?

Accepted Answer

Electron

Question 6

A neutral atom of oxygen has an atomic number $$Z = 8. $$How many electrons are present in the $$\mathrm{O}^{2-}$$ anion?

Accepted Answer

$$10$$

Question 7

Which element contains 50 protons in its nucleus?

Accepted Answer

Tin

Question 8

An isotope of argon has a mass number of 40 ($$A = 40) $$and atomic number $$Z = 18. $$How many neutrons does it contain?

Accepted Answer

$$22$$

Question 9

Which of the following best describes a metalloid?

Accepted Answer

An element with properties intermediate between metals and nonmetals, often used as a semiconductor

Question 10

Which group of elements is known for being highly unreactive and is commonly used in lighting and balloons?

Accepted Answer

Noble gases

Question 11

A naturally occurring sample of chlorine consists of 75.77% chlorine-35 (mass = 34.97 amu) and 24.23% chlorine-37 (mass = 36.97 amu). What is the atomic mass of chlorine?

Accepted Answer

$$35.45$$ amu

Question 12

Which of the following is a derived SI unit?

Accepted Answer

Liter (L)

Question 13

Convert $$25.0\ ^\circ\mathrm{C} to $$Kelvin using the correct formula.

Accepted Answer

$$25.0 + 273.15 = 298.15\ \mathrm{K}$$

Question 14

Which of the following statements about significant figures is correct?

Accepted Answer

Trailing zeros after a decimal point are significant.

Question 15

A student measures the mass of a sample three times and gets values that are very close to each other but far from the actual value. This is an example of:

Accepted Answer

Low accuracy, high precision

Question 16

Which of the following is an intensive property?

Accepted Answer

Density

Question 17

Which of the following best describes the difference between a compound and a mixture?

Accepted Answer

A compound is a pure substance composed of two or more elements chemically combined, while a mixture is a combination of substances not chemically bonded.

Question 18

Which of the following is the correct formula for converting Fahrenheit to Celsius?

Accepted Answer

$$^\circ\mathrm{C} = (^\circ\mathrm{F} - 32) / 1.8$$

Question 19

Which of the following is a correct statement about ions?

Accepted Answer

Cations are positively charged and anions are negatively charged.

Question 20

Which of the following best describes the periodic law as formulated by Mendeleev?

Accepted Answer

When elements are arranged in order of increasing atomic mass, certain sets of properties recur periodically.

Fundamentals of General Chemistry: Matter, Atoms, Elements, and Measurement

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